For dynamo electric machines



B. W. SWEET.

BRUSH HOLDER FOB DYNAMO ELECTRIC MACHiNES. APPLICATION FILED AUGJ. 1915.

. 1,307,028. Patented June 17,1919.

UNITED STATES PATENT OFFICE.

BURTON W'. SWEET, F CLEVELAND, OHIO, ASSIGNOR TO VAN BORN ELECTRIC TOOL COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

BRUSH-HOLDER FOR DYNAMO-ELECTBIC MACHINES.

Specification of Letters L Patent.

Patented June 17, 1919.

Application filed August 7, 1915. Serial No. 44,208.

tain new and useful Improvements in Brush-Holders for Dynamo-Electric Machines, of which the following is a specification.

My invention relates to improvements in brush holders for dynamo electrlc machines,

and has for its object, the construction of a compact and simple brush holder especially designed for multi-polar machines, which will permit of readily inserting and remov ing the brushes.- while insuring adequate conductivity, as well as maintaining the desired pressure or tension upon said brushes. Other structural features will be explained in connection with the preferred embodiment of my invention which is disclosed in a brush holder for accommodating some four carbon brushes and maintaining them in contact relation with the commutator.

The features of this device will be better understood by first making reference to the accompanying sheet of drawings, wherein: V

' Figure 1 is a front viewvof the multipolar brush holder device embodying my invention,

Fig. 2 is a rear view thereof, and Fig. 3 is a fragmentary view upon a larger scale with the parts partially broken away. Fig. 4 is another enlarged fragmentary edge-view of said brush holder. Fig. 5 is a cross-sectional detail. The same character of reference is employed throughout the figures to indicate similar parts.

The annual insulating base a of my device pivotally mounts four spring-pressed arms I), which respectively are associated with the stationary guides c for accommodating their fiat carbon brushes (1. These brushes d are shown in Figs. 1 and 2 in position of yieldingly engaging the commutator 6.

Each of said arms (1 is mounted upon a pivot pin f, these being diametrically positioned in opposing pairs. The upper and lower pivot pins, as will be noted by referring to Fig. 2, are electrically connected by means (if a conductor f embedded in the inwardly channeled, annular cover-member 9, while the horizontally extending pivot pins are electrically connected by means of the conductor 7, also embedded in said annular cover-member; these conductors being disposed in separate concentric channels as shown by full and dotted lines.

As will be better understood by referring to Figs. 3 and at, each of said pivot pins is equipped with a coiled spring h, having an outer terminal pin it, adapted to be seated in any of the numerous depressions 6, provided about the hub of the arm 6. Thus, the tension of the spring in its re-action against said arm, may be readily adjusted for the purpose of depressing the individual brush within its holder, while the conduc tivity of the pivoted parts is enhanced by means of the rectangularly bent inner terriorly positioned spring 6 is adapted to be depressed and engage the end of said terminal pin upon its insertion within the receptacle whereby contact is established directly with the brush. By this arrangement, the brushes may be readily renewed, while securing the advantages of a permanent connection with the spring actuated arm. Moreover, as the brushes are capable of partial removal from,

the guides, they may be held out of engagement with the 'cominutator by elevating them as shown in Fig. 3, and permit the arm to bear laterally against said brushes, instead of upon their ends, so that the commu tator may be inspected and any necessary attention given thereto, and to the brushes themselves, without actually removing said brushes from the holder.

While the brush may beelevated out of contact with the commutator, as just explained, it is not necessary to disconnect the terminal (5 and the conductor (Z from the arm. Thus, the device may be promptly restored to its working condition, as shown in Figs. 1 and 2. From a consideration of the structure just described, it will be seen that unusually effective contact is insured between the conductive parts, inasmuch as electrically unite the rear extensions f, 7",

' of the pivot pins. These pivot pins, inturn,

are terminally engaged by the coil springs 71, Whiclnrespectively place the pivot-arms under tension. The arms, in turn, have spring and plug connections with the conductors attached to the several brushes, so that no defective connections are possible throughout the device.

Referring particularly tol igs. l and 5, the means for initially adjusting the tension of the coil spring h, will be readily understood. The sleeve 2', is stationary with the base, while the screw-healed pivot pin f, is rotatable therein. Qu d holes, f,,are bored in the shank of said pivot-pin, while a spring-key, 7c, is adapted to pass through said holes when in register wi h corresponding holes a", bored in said sleeve. By using a screwdriver, and rotating the pivot in a clockwise direction, an initial tension of any desired amount may be placed upon .the spring it, suitable to the particular requirements, with the pin it engaging the outer slot of the arm I). As the brushes wear away, the pin it", may be moved back successively, into the four additional depressions therefor in the hub of the pivot arm, corresponding to the wear of the brush, so that the given set of tension spring h, upo the pivot pin, need not be altered.

Accordingly, my improved brush-holder, which is adapted for dynamo-electric machines of moderate size, and for small electric tools, requires less adjustment and attention than other similar devices, and more readily lends itself toprompt adjustment, and for giving attention to the commutator, than do other brush-holders with which I am acquainted. The brushes may be quickly raised or lowered in their respective guides or sockets, and the individual tension of their springs may be set to conform with the conditions of wear, so that brushes of different lengths may be used with equal facility.

Having now described the preferred embodiment of my invention, I 'claim as new, and desire to secure by Letters Patent, the following 1. In a brush-holder device, the combination with a socket-member for receiving a brush, of a pivoted arm adapted normally to bear againstthe end of the inserted brush, a flexible conductor connecting the arm and memes annular grooves.

3. In a brush-holding device, the conibif nation with an insulating base, of a brushholder and socket, wherein the brush is adapted freely to slide, a pivoted arm adjacent to said socket and positioned alternatively to bear against the end of the inserted brush, or against its side, when said brush is partially withdrawn, and a tension spring for exerting pressure through said arm upon the brush, substantially as set forth.

a. In a brush-holder for dynamo electric machines, the combination with a guide for supporting the brush, of a brush loosely sliding therein, a spring-actuated arm react ing against the brush, a flexible conductor connecting the arm and said brush, means i for adjusting the initial tension of said arm and additional means for compensating the wear of the brush, whereby to obtain substantially uniform pressure upon a commutator, substantially as set forth.

5. In a brush-holder for dynamo electric machines, the combination with a guide for supporting the brush, of a spring actuated arm reacting against'the brush, a coiled spring adjustably attached to said arm, adjustable attaching means and independent means for placing an initial tension upon said spring, comprising a rotatable detent for the inner end of the spring and a securing part for said detent, substantially as set forth.

6. In a brush-holder device, the combination with a brush-receiving member, of a pivoted arm adapted normally to bear upon the brush, a tension spring therefor, and means for adjusting the spring tension from both of its extremities, substantially as set forth.

In testimony whereof I do hereby affix my signature in the presence of two wit nesses.

BURTON W SWEET.

Witnesses FRANK BUHNA, ALBERT Lynx LA.\RENCE. 

